US3309517A

US3309517A - Electrostatic separator which utilizes electrodes with a shape of geometrically periodic delay lines

Info

Publication number: US3309517A
Application number: US302101A
Authority: US
Inventors: Liot Raymond
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-09-04
Filing date: 1963-08-14
Publication date: 1967-03-14
Anticipated expiration: 1984-03-14
Also published as: GB982908A; DE1498644A1; FR1340272A

Description

March 14, 1967 v 0 3,309,517

ELECTROSTATIC SEPARATOR WHICH UTILIZES ELECTRODES WITH A SHAPE OF GEOMETRICALLY PERIODIC DELAY LINES Filed Aug. 14, 1965 UUUUUUHUUUD INVENTOR :RLIOT BY 70ml who; I

United States Patent 3,309,517 ELECTRQSTATIC SEPARATOR WHICH UTILIZES ELECTRODES WITH A SHAPE OF GEOMETRI- CALLY PERIODIC DELAY LINES Raymond Liot, 79 Blvd. Haussmann, Paris, France Filed Aug. 14, 1963, Ser. No.,302,101 Claims priority, application France, Sept. 4, 1962,

908,514 Claims. (Cl. 25041.9)

The present invention relates to improvements in electrostatic separators for use with particle accelerators.

It is known that the beam of accelerated particles leaving an accelerator, in particular, a beam of heavy particles is not in general pure, that is, does not contain the particles of one and the same mass and velocity, but contains mixed particles of different species and types, having a momentum substantially the same but of different masses, and, consequently, different velocities inversely proportional to the masses. If one desires, for a given research in physics, to have a pure beam, it is necessary to proceed with the separation of the particles of desired mass from those having other masses.

It is known to make this separation with the aid of electrostatic separators, constituted in principle of a condenser between the electrodes of which one causes to pass the beam from the output of the accelerator, across the direct-current electric field established between these electrodes. The particles of different velocities follow within this field different trajectories or paths and undergo a deviation or deflection of which the amplitude at the output of the condenser is inversely proportional to the momentum and to the velocity of the particle, that is, with a constant quantity of momentum, inversely proportional only to the velocity. These different paths are thereupon intercepted by the utilization devices of the particles which are desired or absorption devices for those which are not desired.

A transverse magnetic field, crossedwith the electric field, may additionally be established either across the space between the electrodes of the condenser or across the space traversed by the trajectories or paths of the particles ahead of and/or behind the condenser, with a view to diminish the chromatic aberration and to increase thus the reciprocal separation of the trajectories without overlap, and in addition to disperse the paths or trajectories with deviation in one or the other direction or even without deviation.

The same separators may also be utilized to extract the particles of a given energy of a beam which, though pure from the point of view of mass, is not mono-energetic,

that is, of which the particles of same mass leave the accelerator with velocities distributed within a certain spectrum.

In order to obtain an efficient separation along a reduced path, it is necessary to establish within the condenser an electric field which is as intense as possible, that is, to establish between the electrodes a difference of potential as high as possible.

A limitation in this approach is the appearance, beginning with a certain voltage, of sparkovers between the electrodes carried at the high voltage, sparkovers which, in the known prior art separators, are followed by steady arcs producing a short circuit with circuit interruption of the high voltage supply source, and with the necessity to stop the experiments during the time of reapplying the voltage.

The object of the present invention is an electrostatic particle separator in which this inconvenience is eliminated, that is, in which the sparkovers, to the extent to which they are still produced, remain intermittent without being followed by permanent arcs and do not add to the 3,39%,517 Patented Mar. 14, 1967 substantial disturbance of the operation of the installation.

The invention is based on a certain hypothesis of applicant herein as regards the mechanism of formation of these arcs; however, it must be understood that the present invention does not depend in any way on the validity of this hypothesis.

It is known that the occurrence of a spark between the electrodes of a condenser is a generator of an entire spectrum of high frequencies, and applicant assumes that within the spectrum there is also always a frequency with respect to which the assembly of the two electrodes in question constitutes a bi-filar open line with high Q factor and along which a very high amplitude of the wave will be produced therefore at the frequency in question. It is this amplitude which therefore would be responsible for entertaining the sparking and the transformation of an intermittent spark into a permanent arc.

To remedy this disadvantage, it is appropriate therefore to diminish the Q factor, and a possible means would consist in damping the circuit by constituting or covering the electrodes with a material of poor conductivity, such as graphite, semi-conductors, resistant alloys, etc.

However, these means would be impractical, for such materials or coatings would be damaged at more or less brief intervals by the intermittent sparks that subsist between the electrodes under high voltage, thereby produc ing evaporation or discharge of gases disastrous for the electrodes and adjoining parts.

The present invention therefore proposes other means consisting in giving to these electrodes the structure of a delay line, known per se in the construction of microwave tubes.

According to one development of the present invention, resistances may be introduced into the structure of such delay lines.

Accordingly, it is an object of the present invention to provide a particle separator of the type mentioned hereinabove which effectively eliminates the shortcomings and disadvantages cited hereinabove and encountered with the prior art constructions.

Another object of the present invention resides in the provision of an electrostatic separator for use in particle accelerators which eliminates by simple means the danger of sparking and lasting arcing.

Still another object of the present invention resides in the provision of an electrostatic separator for particle accelerators which assures uninterrupted experiments without dangers of short circuits within the separator.

A further object of the present invention resides in the provision of an electrostatic particle separator, particularly for heavy particles leaving an accelerator, which precludes the possibility of permanent arcs within the separator without danger of contamination to parts thereof by evaporation or discharge of harmful gases.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein:

FIGURE 1 is a longitudinal cross-sectional view through a separator according to the present invention within an accelerator installation indicated only schematically;

FIGURE 2 is a transverse cross-sectional view of the separator of FIGURE 1, taken along line IIII of FIG- URE 1;

FIGURE 3 is a partial elevational view of a first embodiment of an electrode structure of the separator according to the present invention;

FIGURE 4 is a partial elevational View of a second embodiment of an electrode structure of the separator in accordance with the present invention;

FIGURE is a partial elevational view of a third embodiment of an electrode structure of the separator according to the present invention;

FIGURE 6 is a partial transverse cross-sectional view through the electrodes formed in accordance with the embodiment of FIGURE 3, with a modification according to a further development of the present invention; and

FIGURE 7 is a partial transverse cross-sectional view of an electrode element formed in accordance with the embodiments of FIGURES 4 or 5, with a further modification according to the present invention.

Referring now to the drawing, wherein like reference numerals are used throughout the various views to designate like parts, and more particularly to FIGURE 1, the rectangle 1 represents schematically a particle accelerator of which the beam 2 enters into a particle separator comprising, within a metallic cylinder 3 open at both sides thereof, a pair of

electrodes

4 and 5 carried respectively at the high positive and negative voltage with respect to the grounded cylinder 3, and consequently forming the plates of a condenser.

As an illustrative example, it is assumed that the space between the

electrodes

4 and 5 is traversed by a transverse magnetic field furnished by the pole pieces 6 and 7, shown in FIGURE 2, in such a direction that the Lorentz force exerted by this field on the particles in movement opposes the electric force exerted on these same particles by the electric field due to the difference in the potential applied between the

electrodes

4 and 5. However, as known, the separator could function also without this magnetic field, or the magnetic field could be established to traverse the spaces between the output of the accelerator 1 and the input of the cylinder 3 or after the output from the cylinder 3. As is known, the beam 2 is divided within such separators into a plurality of trajectories such as 8, 9 and 10 dependent on the velocity of the particles which follow these trajectories; along the paths of these trajectories are disposed utilization or

absorption devices

11, 12, and 13 for the utilization of the particles which have the desired velocity or the absorption of the particles which are of no interest.

According to the present invention, the

electrodes

4 and 5 of the separation condenser have a delay line structure known in microwave tubes, for example, in the form of a ladder with plain bars or rungs (FIGURE 3) or cut rungs (FIGURE 4) or in the form of an interdigital line (FIG- URE 5). Each of these forms comprises

longitudinal supports

14 and 15 to which are fixed respectively the bars or rungs 16 (FIGURE 3) or the fingers 17 and 18 (FIG- URES 4 or 5).

According to a further development of the present invention, damping resistances are interconnected within the bodies of the described or analogous structures. To that effect, the delay line, for example, of FIGURE 3 will be transformed by separating the bars or rungs 16 from the supports 14 and 15 (FIGURE 6) and by shunting the intervals of separation by means of resistances 19. In an analogous manner, one will separate, within each of the combs composing the lines according to FIGURES 4 and 5, the fingers 17 from the supports 14 or the fingers 18 from the support 15, and one will then shunt the intervals of separation by resistances 19 as shown in FIG- URE 7.

The realizations described in a non-limitative manner as well as all other equivalent realizations utilizing the exposed principles, bring about an important improvement to the operation of electrostatic particle separators, which operation is only slightly disturbed by the intermittent sparkovers whereas the more or less permanent arcs which would necessitate shut-down times in the operation, are suppressed or at least strongly reduced.

While I have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible of numerous changes and modifications as known to a person skilled in the art, and I therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

I claim:

1. In a electrostatic separator for separating charged particles contained in a particle beam said charged particles having individual momentum values resulting from at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, the improvement essentially consisting of:

a spaced pair of mutually facing electrodes with a shape 7 of geometrically periodic delay lines,

means for applying an electrostatic potential difference between said electrodes,

and means for directing the particle beam through the space between said electrodes.

2. In an electrostatic separator for separating charged particles contained in a particle beam said charged particles having individual momentum values resulting from at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, the improvement essentially consisting of a spaced pair of mutually facing electrodes with a shape of geometrically periodic delay lines, at least one of said electrodes having the shape of a ladder-type delay line including rungs substantially perpendicular to a pair of longitudinal bars,

3. In an electrostatic separator for separating charged particles contained in a particle beam said charged particles having individual momentum values resulting from at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, the improvement essentially consisting of:

a spaced pair of mutually facing electrodes with a shape I of geometrically periodic delay lines, at least one of said electrodes having the shape of a ladder-type delay line including rungs substantially perpendicular to a pair of longitudinal bars, means for applying an electrostatic potential difference between said electrodes,

and means for directing the particle beam through the space between said electrodes,

said rungs being cut substantially in the plane of longi tudinal symmetry of the delay line to separate the ladder into a pair of mutually facing comb-type structures. p 4. In an electrostatic separator for separating charged particles contained in a particle beam said charged particles having individual momentum values resulting from at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, the improvement essentially consisting of:

a spaced pair of mutually facing delay line electrode structures at least one of said electrode structures having the shape of an interdigital delay line,

5. In an electrostatic separator for separating charged particles contained in a particle beam said charged particles having individual momentum values resulting from at least one dilferent parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, the improvement essentially consisting of:

a spacedpair of mutually facing delay line electrode structures at least one of said electrode structures being composed of a pair of comb-like structures provided with fingers substantially perpendicular to a longitudinal bar,

6. An electrostatic separator for separating charged particles contained in a particle beam said charged particles having individual momentum values resulting from at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, said separator comprising:

a spaced pair of mutually facing delay line electrode structures at least one of said electrode structures being composed of a pair of comb-like structures, provided with fingers substantially perpendicular to a longitudinal bar,

said fingers being mechanically separated from the bar to provide spaces between said fingers and said bar, and resistive means connected across said last mentioned spaces.

7. An electrostatic separator charged particles contained in a particle beam said charged particles having individual momentum values resulting from at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, said separator comprising:

a spaced pair of mutually facing electrodes with a shape of geometrically periodic delay lines,

at least one of said electrodes having the shape of a ladder-type delay line including rungs substantially perpendicular to a pair of longitudinal bars,

said rungs being mechanically separated from said bars to provide spaces between said rungs and said bars, and resistive means connected across said last mentioned spaces.

8. In an electrostatic separator for charged particles contained within a particle beam said charged particles having individual momentum values as a result of at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, including electrode means operable to establish a transverse electrostatic field upon application of a high potential difference between the electrode means to separate out the particles according to the momentum values thereof as they pass through said electrostatic field,

the improvement essentially consisting of means for preventing the establishment of permanent arcs across said electrode means by lowering the Q factor of said electrode means for a given frequency, within the frequency spectrum of a transient sparkover between said electrode means,

said means including a plurality of mutually facing spaced electrodes with a shape of geometric periodic delay lines.

9. In an electrostatic separator for charged particles contained within a particle beam said charged particles having individual momentum values as a result of at least one difierent parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, including electrode means operable to establish a transverse electrostatic field upon application of a high potential difference between the electrode means to separate out the particles according to the momentum values thereof as they pass through said electrostatic field,

the improvement essentially consisting of means for preventing the establishment of permanent arcs across said electrode means by lowering the Q factor of said electrode means for a given frequency within the frequency spectrum of a transient sparkover between said electrode means,

said means including spaced delay line circuit means having a plurality of delay circuit elements and damping means connected across adjacent elements of said delay circuit means.

10. In an electrostatic separator for charged particles contained within a particle beam said charged particles having individual momentum values as a result of at least one different parameter of the two momentum parameters consisting of mass and velocity, respectively, of each particle, including electrode means operable to establish a transverse electrostatic field upon application of a high potential difference between the electrode means to separate out the particles according to the momentum values thereof as they pass through said electrostatic field,

said means including a spaced pair of mutually facing electrodes with a shape of geometrically periodic delay lines.

References Cited by the Examiner UNITED STATES PATENTS 2,779,006 1/ 1957 Albersheim 333-81 2,868,986 1/1959 Lanneau et al. 25041.9 2,915,715 12/1959 Young 33381 2,942,142 6/1960 Dench 315-3.5 3,016,458 1/1962 Blewett 250-41.9 3,093,733 6/1963 Blewett et al. 250-41.9

RALPH G. NILSON, Primary Examiner.

W. F. LINDQUIST, Assistant Examiner.

Claims

1. IN A ELECTROSTATIC SEPARATOR FOR SEPARATING CHARGED PARTICLES CONTAINED IN A PARTICLE BEAM SAID CHARGED PARTICLES HAVING INDIVIDUAL MOMENTUM VALUES RESULTING FROM AT LEAST ONE DIFFERENT PARAMETER OF THE TWO MOMEMENTUM PARAMETERS CONSISTING OF MASS AND VELOCITY, RESPECTIVE, OF EACH PARTICLE, THE IMPROVEMENT ESSENTIALLY CONSISTING OF: A SPACED PAIR OF MUTUALLY FACING ELECTRODES WITH A SHAPE OF GEOMETRICALLY PERIODIC DELAY LINES, MEANS FOR APPLYING AN ELECTROSTATIC POTENTIAL DIFFERENCE BETWEEN SAID ELECTRODES, AND MEANS FOR DIRECTING THE PARTICLE BEAM THROUGH THE SPACE BETWEEN SAID ELECTRODES.